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k Is k '^ Y. k BOUNDARY SURVEY 



BY 



OTTO JULIUS KOLTZ 



FROM 
POPULAR ASTRONOMY 
MARCH APRIL 1896 



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W. W.Payne. 347 

vanced our knowledge of them greatly during the last two years. 

It is a natural question to ask wh}'^ it is that all this detailed 
knowledge of the surface of Mars was not observed by others 
sooner, especially after its announcement by Schiaparelli. It 
could not be that his telescope was better than all others, for it 
was a small one. It could not be that his sharp and trained eye 
was so much superior to all others, that what he could see w^ell 
and minutely describe should be wholly invisible to all other ob- 
servers for a period of nine years after announcement. This 
question almost more than any other has interested astronomers 
very greatly of late, and induced thoughtful study of it as never 
before. The trial of mountain stations for observation, those in 
regions of quiet, clear air of lower altitude and those of broad 
high plateaus have all been made, to learn by actual use the best 
conditions for difficult telescopic work. The planet Mars has re- 
cently been in favorable position in regard to distance from the 
Earth for the study of surface markings, and the opportunity has 
been most diligently and persistently used by the aid of telescopes 
of all sizes and in all favorable latitudes for the sake of learning 
something new and helpful in making astronomical observations 
that would bring into use the hightest powers of the modern 
telescope. 

Those who desire the sources of best information in regard to 
what is now known about the planet Mars, and a delightful ac- 
count of how astronomers have gained their knowledge should 
read t'wo important books: one by CamilleFlammarion, of Paris, 
published in 1892, and the other by Percival Lowell, of Boston, 
recentl}? published by Houghton, Mifflin & Co. Flammarion's 
book v/as by far the most complete and comprehensive study of 
Mars that had appeared up to its date. It is indeed a scholarly 
compendium of what was known of the planet, involving much 
illustration and great pains-taking in gathering materials. On 
the other hand Mr. Lowell showed good judgment in not at- 
tempting to write another book on the same subject like that of 
Flammarion, but by the aid of a fine 18-inch refractor he has 
tried most industriously and effectively to widen the range of 
knowledge concerning a score of vitally interesting questions 
chiefly about the phj'sical conditions that exist on the planet 
Mars. How well he has succeeded in this any thoughtful reader 
can judge for himself after a perusal of his book which is written 
in plain popular language, but crowded with an arra}' of facts 
that are made tosignify much that isnew by thegifted and ready 
reasoning power which Mr. Lowell possesses as a writer, in a re~ 



a^-S Aluskn Boundary Survey 



markabic degree. Later wc wish to make n carcliil comparison 
of his views wliich are decnicHl new with those of others Ijearing 
on tlie (|ucstioii of Martian atmosphere, temperature, canals, 
water iminiiation. desert re^'ionsand other similar features which 
Mr. LoweU's hook discusses. 



ALASKA BOUNDARY SURVEY. 

OTTO J. KLOT/C. 



PoH rolTl.AH ASTHONO.MV. 

The surveys that have been made during the past three years 
were not made witli the object of defining the boundary line of 
southeastern Alaska, but for the ]nirpose of gathering data so 
that the question of delimitation may l)e more intelligenth' dis- 
cussed, prior to actual marking on the ground. The survey was 
carried on under a joint Commission, \V. F. King being Her 
Majesty's Commissioner, and T. C. Mendenhall, now succeeded 
by Genl. \V. \V. Dufiield, Superintendent of the Coast and Geo- 
detic Survey, rejiresenting the United States. 

In 18i)3 the V . S. Coast and Geodetic Survey had twelve officers 
in the field, of whom three had charge of parties, three were as- 
tronomers and the remaining six were attached to six Canadian 
survey parties. Canada had seven parties in the field and all 
engaged in topographic work. There was a Canadian represen- 
tative, too, on each of the United States Stikine and Taku 
River parties. Furthermore each country had a vessel for inter- 
communication between the parties. 

The area covered by the Canadian parties during this season 
included nearly all the territory adjoining the shore line from 
Burrough's Bay or the Unuk River which emi)ties there, to the 
west side of Taku Inlet. 

The United States parties were engaged in the survey of the 
Stikine and Taku Rivers and Taku Inlet; and in the determina- 
tion of the latitude and longitude of the mouth of the Unuk, 
Wrangell, and the mouth of the Taku. Sitka served as base 
station for longitude, whence chronometers were carried fort- 
iiightlv by the United States survey vessel to the three astro- 
nomic stations mentioned. In 1894 the operations were con- 
tinued and extended, and on similar lines. The close of this 
season left little remaining to be done for the present. Canada 
had only one party in the field this year (1895), and its work 
was along the base of the Mt. St. Elias Alps, 



otto J. Klotz. 349 

Of the methods of work in the field I will only speak of those 
adopted by Canada. 

Knowing beforehand the intensely mountainous character of 
the country under discussion, it was obvious — based on experi- 
ence in the Rocky Mountains — that the most practical and cheap- 
est method for a topographic survey was by means of the 
transit and camera. The idea of the application of the camera 
for topographic purposes is not new, but its practical applica- 
tion on a large scale is of recent date. Germany, France and 
Italy have done photographic work, but only the last named 
country has done any on an extensive scale. However, Canada 
has done considerably more, and has raised the art from its ex- 
perimental stage to one of permanency, through the labors of 
her Surveyor General, E. Deville. 

Without following photo-topography through its various 
stages of development in Canada, we will confine ourselves to a 
statement of the modus operandi of the Boundary Survey. 

The greatest drawback to the progress of the work was the 
continuous saturated condition of the atmosphere showing 
itself either as rain, fog or fog banks, and clouds so that the 
area covered by survey in a season is not a fair estimate of 
what the parties could have accomplished under ordinary 
climatic conditions. Many a time did an early morning bode 
a fair day, when a start would be made from a seashore where 
camp was almost invariably pitched, for an ascent of perhaps 
five thousand feet, only to find after hours of scrambling through 
Devil's Club (Fatsia horrida), knee-deep moss, windfalls, alder 
brush on land slides; then emerging through timber line onto 
rock and snow and glaciers with their treacherous crevasses; 
skirting chasms and abysses, at times with only slender foot-hold 
to save from the yawning depths; again lying full length with 
arms extended on smooth, slippery glaciated rock and creeping 
along, onward — upwards to the goal, and when reached, oneself 
enveloped in a bank of clouds hovering around the peak and 
completely shutting out the world. Perhaps it will lift is the 
ardent hope. One waits, shivers. At times it snows to add to 
the discomfort, often miser3^ In vain, the day advances, the Sun 
is seeking its western home, and with faint heart the party has 
to begin the descent. It is made more quickly than the ascent 
but often with more danger, as the men indulge in the expedi- 
tious method of glissade — sliding on the ice or snow^ crest with 
the imminent danger of a crevasse or precipice. But camp, like 
the word home, has a magic and magnetic spell. Almost nothing 
save destruction stops the powerful attraction. 



350 Alnsku Iloiuuhiry Survey. 

However dishearteninp^ such work is, success can onl\- be ac- 
complished by workin;^ until one ck)es succeed. Hence many a 
mountain peak was climbed more than once, one in fact ci«^ht 
times. Success is good naturcd and immediately forgets all pre- 
vit)us trials and tribulations. The season of 1893 ditl not give a 
dozen really gootl days for instrumental and photograpliic work. 

A good view from a peak has been aptly described by 

" What a scene of (ksolalioii 
1 saw Irom llie mDiintain ]>eak; 
Cra^s. snowtields, ;ilaeiatioii, 
rnuttcrable to sjjcaU." 

The shore hue of the northwestern part of the continent is very 
tiuieh indented by bays, inlets and fn)rds or canals. Adjoining 
the sea the vegetation is rank, and the luxuriant mosses and 
ferns give it a semi-tropical ap])earanee. Tind)er line is reached 
at about 2,500 feet. The forest is almost exclusively coniferous. 

Nearly the whole of the shore of tlie territory under considera- 
tion has been surveyed and charted by ofhcers of the Tnited 
States Xavy, and this, in a mciisure, served ^is a l)ase for the 
topographic work. However, e£ich party meiisured, by means of 
steel tape, a Ijase line at some ktiown point on the shore, and 
from ic expanded a triangulation over the area wliose topogra- 
])hy was to be delineated. It is scarcely necessary to state that 
for mountain work everylhitig must be made as portrible as pos- 
sible, and instruments reduced to a minimum ot weight. 

The outfit of each jjarty consisted of a Troughton c\: Simms 
3-ineh transit theodolite in a leatlier covered box and carried like 
i\ knapsack ; an extension tripod ; a camera, to be described more 
fully hereafter; several anerc>itls by Hughes; a sidereal chrt)nt)me- 
ter; a field glass, and one or two box compasses; and each ir.an 
was j)rovided with the indispensible alpetistock. For transport 
each party was supplied with one Mackinac boat, which served 
its purp(3se admirably, and one or two Peterborough canoes, 
those marvelous water sprites that dance on rai)ids or on the 
ocean billows with a steadiness wonderful. I recollect one of 
of our American iViends thought them at least "cranky " looking 
and had some hesitation in getting into one of them, saying that 
for safety he ought to liavc his liair ])arled in the middle. 

Both the horizontal and vertical circles of the transit read to 
minutes of arc. Angles were read in the usual way, /. c, one set 
—circle right; the other— circle left. The sides of the triangles 
were mostly between six and ten miles, although distant ])caks 
\vere tied by sides upA'ards of forty miles long, and St. lilias b}' 



Otto J. Klotz. 351 

lines over sixty miles long. It may be stated right here that the 
photographs of these latter distances came out sharp and clear 
and flat, and were hence available for outline topographic pur- 
poses. At each station horizontal and vertical angles w^ere read 
on all the principal peaks and points in the terrene. From the 
horizontal angles the triangulation or skeleton, upon which the 
topography is based, is obtained ; and from the vertical angles 
the heights of such peaks, which are later checked by the photo- 
graphs themselves. As some of the peaks occupied were isolated, 
sharp and well defined, signals or cairns were not placed at all 
the summit stations. The azimuth was controlled by solar ob- 
servations Vk'hen obtainable. Stellar observations were imprac- 
ticable at mountain stations, although some were taken at sea 
shore. 

As the camera is the characteristic instrument of the Canadian 
Survey, a somewhat detailed account of it will be given. As be- 
fore intimated, the camera, in its present form, is the outcome of 
yearly experiments and experience since its first application by 
Canada in the Rocky Mountains in 1886. 

The first distinctive feature about the camera is that it has no 
focusing adjustment, as all views taken are distant, the rays are 
practically parallel and converge at the same distance from the 
lens. The camera box is therefore very rigid, of well seasoned 
mahogany and brass bound. For use it is attached to a brass 
foot with levelling screws, and held by a stout screw, with milled 
head, passing through the middle of the foot, and into a brass 
block in the box. The foot itself fits onto the transit tripod, the 
latter serving for both instruments. 

As it is essential that the camera be horizontal, it is provided 
with two levels in the form of a T, attachable to a brass grove 
on top of the box. In the middle of each side and directly in front 
of and close to the sensitive plate is fixed a narrow (%'') brass 
comb. The four are consequently photographed on each view^ 
and serve the purpose of readily drawing the horizon and princi- 
pal Hues on the photograph or enlarged print, for these are the 
lines of reference or axes of coordinates for interpreting the 
prints. Each camera is provided with six double holders, num- 
bered and carrying a dozen glass plates, which are generally suf- 
ficient for a day's climb. The plates are 4% x 61/2", isochromatic 
and made by Edwards, London. The plates before being put 
into the holders are marked in one corner with consecutive num- 
bers, together with the initial of the chief of party, and a note is 
made of the corresponding number of the holder, so as to be able 



352 Alaska Boundnry Survey. 



to enter in the field book, when exposing, the number of the neg- 
ative, its corresponding station and view. Each party was ])ro- 
vidcd witli a small black tent, lined with red, and a red light 
lantern for changing i)latcs. The tent was just large enough to 
admit one, and was generally suspended from the ridge pole in 
one of the camp tents and overhanging the small camp table, so 
that the changing could be done with ease and comfort. There 
being really no night in midsummer in Alaska, it would scarcely 
be safe to change in an ordinar}' tent, even at midnight. The 
camerti could also be set on end on the tripod. This was for the 
jjurpose of being rdjle to ])hotograph deej) ravines or canons 
where the vertical element exceeded the horizontal. 

The lens or objective is a wide angle one: by Dallmeyer, London. 
Between the two lenses forming the objective is inserted the dia- 
jjliriigm or stop. Of those sup[)lied with each camera, the smal- 
lest one Vs" is always used. The focal length of the lens is 5%". 
The lens screws onto the detachable front piece of the camera, 
and when not in use is carried in a leather C£ise. In screwing it 
in place it is alwavs brought up to the mark cut on the collar so 
as to preserve a uniform distance from the sensitive plate. 

(TO BE CONTINUED.) 



Note. — Forgiving an idea of the country in which the work was carried on, 
and also of the result of photographing distant views the reproduction of pho- 
tographs is given as frontispiece. 

One of our grandest views is that of photographs covering parts of the vast 
complex of the Muir Glacier System. 

On view No. 1 will be noticed the comi) marks in the middle of the sides. The 
two straight lines joining the proper points on opposite combs constitute the 
axes of rectangular co-ordinates for measurements on the photograph. This 
view is taken from an elevation of 5913 ft. The station is situated between the 
two main branches of the Baird Glacier emptying into the northern part of 
Tliomas Bay, Frederick Sound. The pointing of the camera is southeasterly, 
across the eastern branch and along one of its aHliients onto the Devil's Thumb, 
(shown on left hand side) 910") ft. hi.nh, and distant si.xteen miles. Most of the 
other mountains shown are more distant, some over thirty miles. 

Comijaring this photograph with ones taken about Borrough's Hay — in gen- 
eral with those of the more southerly areas where the heights are niostlv con- 
fined to heights of less than six thousand feet — a marked contrast is noted and 
that is, that mountains of less than the latter height are invariably rounded 
showing no sharp pinnacles or peaks, while those to the north, exceeding such 
height, have very angular and sharp crests. The former have been subject to 
glacial abrasion, the latter not. /. e., not above say six thousand feet. 

View No. 2 is from a station, altitude 4-,H81 ft., on the east side of Thomas 
Ba\', and looking northeasterly, also showing the shaft of the Devil's Thumb. 
This station with the preceding one and the Devil's Thumb form approximately 
an c(|uilaleral triangle of IG-mile sides. It will thus be seen that these two views 



Alaska Boundary Survey. 39o 



''1^:^:;,^^^^^^^^'^^^^ described in detail with such ac- 

The ^^^^^'^^ Haven instrument as was necessary to show 

Thrnature ontroperation. The diameter of the Earth's orb^ 

'the bl^e Hne for measurement of parallax and accordingly ob- 

.fions of the position of the star are taken at intervals of 

servations of ^^ e P^« ^^^^^ed with reference to its 

^Ino:::" ^-.e Z,Zr To^panion stars in four directions being 

:j;:r;i: this ^mp.rison. The ^^^^ 

suited from these measurements is the paiallax, anu 

™«v be determined the distance of the star from us 

Of -e nature is the problem of the distance of the St,n, and 
n°on this Dr Ell n has' been at work with results which at first 
were ree ived with caution on account of their apparent small- 
Tess b„ Thich have since been supported by new determ.nattons 
n other ways. The close relationships which have been proven 
between The elements which compose our solar system are such 
tharthe exact determination of the distance of any one planet 
win afford a means of computing all the other d.menstons and 
di ances It was therefore suggested that the observat.ons of 
Ip nt the asteroids might be of value, and accordingly Dr. 
ElSn made a s'tes of mea'sures of Sappho and Victoria, wuh a 

"ifaddi'lio'lrofttt matters attention has been given at New 
Haven to he triangulation of some seventy stars ,n the Pletades, 
fachof which was independently measured for pos.tton at mter- 
vals, standard stars ontside of the group hav.ng been selected 

'" Ttniffe'ent accomphshments," said Dr. Chandler in finish- 
in. "constitute a record of faithful, zealous, and vigorous prose- 
cution "a tronomy in its very highest plane, and the presence of 
such a man as Dr. Elkin in our country gives standmg and ciedit 
to American astronomy." 



ALASKA. BOUNDARY SURVEY 

OTTO J. KLOTZ. 
For Popular Astronomy. 



For popular amkuixv....^. r +v,a 

The second distinctive and most important feature of the 
camera is the attachment of a plano^glass orange --n to th 
lens. It is screwed to the back of the objective. It is obvious 



* Continued from page 353. 



396 Alaska Boundary Survey. 



that it is (Ifsiial)k' to have on iIk- nc-^alivc not only what we can 
sec, and especially is this true ol the distance, but also that dis- 
tinct and not blurred. Now the ne<ijative or sensitive plate, 
wliich is analogous to the nlina of the eye, is however not sensi- 
tive in the same ineasuie to the visual rays as the retina. Visual 
rays are at the red end of the spectrum and photo<<raphic, or ac- 
tinic at the l)luc end. A ray of li^ht from tiic Sun before reaching 
us surters partial absorption by the atmosphere whicli in turn re- 
fleets and difVuses light. Hence a rellected ray from a distant 
point enters the camera in a depleted state, suffering from loss of 
vigcu". However it could still do effective work if it did not meet 
with the antagonizing energy of the rays — less luminous but 
more actinic — reflected by the atmosphere, so that the weak im- 
print of the former is almost completely annihilated by the action 
of the latter. To overcome the difliculty, or at least to tend 
towards attaining our end, recourse is had to isochronic'itic 
])lates and the orange screen above mentioned. The emulsion of 
these ])lates is colored for intensifying the action of the yellow 
ra^'s which reach it from the distant point, and the orange screen 
for absorbing or cutting ofl' the l)luc rays entering the camera 
from the atmosphere. Photographically s])eidving, we try by 
means of the orange screen to create a vacuum between us and 
the distant view to be photographed so that the rays from there, 
flltei-ed as they are already may have some chance of doing satis- 
factory work. The l)lue haze is the enemy — and it is drowned in 
the artificial yellow sea. For the proper development of the 
negatives some light is necessary and to which the i)late must be 
insensitive. The isochromatic ]ilates used were made insensitive 
to red, and hence were develojjcd under red light. The photo- 
graph of a red object would therefore print black, that is on the 
negative would apjjcar blank. The sensitiveness of the plates 
was confined .almost wholly to ihe yellow part of the spectrum. 
We are therefore from the conditions surrountling us, obliged in 
applying plu)t()gra])liy to topograj)hical purposes, to utilize the 
yellow rays and cut off the more powerful (photographically) 
blue rays. 

Without the inseition of this screen, much of the work accom- 
plished with the camera would have been imjiossible, hence its 
great value. 

In such an essentially humid atmosphere as f»l)tains in south- 
eastern Alaska, extra provision had to be made to keep the 
plates dry, ^md also for the event of casualties on the water. 
Hence tin boxes were provided, each holding two dozen glass 



Otto J. Klotz. 397 

plates. These boxes were water tight and had air chambers, so 
that when containing the plates they would float. 

The field operations with the camera are very simple, yet re- 
quire discretion, and the value of the expert topographer comes 
into play. Having arrived at a summit station, the transit or 
camera is first set up, depending on atmospheric conditions. A 
sketch is made of the horizon, and of the broad features, noting 
specially peaks or other points read on. As the lens takes in 
sixty degrees, seven plates will take in the whole horizon and al- 
low a lap for each one, so as to have one or more points common 
to two photographs for orienting one view from another. As 
there is no ground glass for seeing the field covered, two diverg- 
ing lines are cut or scratched on the top of the camera indicating 
the angle of the lens. Sighting along these one readily sees the 
limits of the view and thereby can give the proper consecutive 
pointings. Every station does not require a complete circuit of 
the horizon. It also happens that the photographs from a peak 
do not show sufficient of detail of valleys, being hidden by the 
configuration of the mountain, whereas, by going a short dis- 
tance — a hundred or so feet from the summit — the desired view is 
obtained. This is done and the direction and distance of the new 
position of the camera from the station noted. In plotting on a 
80 o"oo scale — that of the original office sheets — such camera sta- 
tion may often be taken as co-incident with the triangulation 
station. 

As the plates are exposed a record is made of the numbers of 
the plate, the pointing of the camera and the view taken. The 
time of exposure varies, of course, with the position of the Sun, 
the state of the atmosphere and the nature of the object. As an 
aid in estimating the quality of the light each surveyor carried 
what may be termed an actinometer. It was the size of a large 
locket and contained a continuous strip of sensitive paper. By 
pulling out a short piece and noting the time it took to assume a 
certain tint a fair estimate of the quality of the light would be 
obtained, and the exposure made accordingly. The exposure 
ranged from 6 to 40 seconds. It is satisfactory to be able to 
state that of the 250 dozen plates exposed not a single one 
proved to be worthless. Some were exposed (from necessit^^) 
even when it was raining. 

Each party was supplied with several aneroids, one of which 
was left at camp for continuous reading. A mercurial, Greene, 
barometer was carried on board the Survey steamer, and with it 
the aneroids were compared. The aneroids furnished a ready 



398 AUiskci lioiirid.iry Suivcy 



nicnns of ohtainni*; the apptDxiinate hcijilit of the nioinitnins 
climhcil. Some (^1 the jj.Mrties carried thennotneters too in their 
ascents for taking the temperature of the air so that the aneroid 
reading:: couM l)e more accurately reduced. The final rdtitudcs of 
all points, however, rest on the tri<jonon)ctric determinations 
and those obtained from the photographs based thereon. IVom 
a large number t)f readings of the aneroid which wliere conii)ar- 
able with trigonometric licights, it wiis ((umd that by carefully 
reading the barometer at ascent and descent, and noting the 
temperature of the air by a good thermometer (not attached to 
the aneroid) that the mean will give a fair value say within two 
per cent of the difference of height of the summit and base or sea. 
This applies to mountains upwards of iive thousand feet in 
height. 

Without going into the details of the office work some of the 
salient ])oints connected therewith may be mentioned. From the 
negatives enlargements are made to twice the linear measure,/, e. 
to four times the surface, on bromide paper. The focal length 
and position of the horizon and princii)al lines with reference to 
the comb marks are specially determined by taking a photograph 
of a large building on which three or more horizontal and verti- 
cal angles each arc read. Any field ])hotograi)h in which the 
azimuth and elevation or depression of a number of ])oints have 
been taken furnishes the necessary data tot), in fact thereby we 
have a nieatis of checking for contraction or expansion of the 
jKiper of the print, as the focal length and horizon line for an3- 
camera are constant. The plotting is done on a scale of one in 
eighty thousand. First the meridians and parallels are projected, 
then the triangulation is jilotted. 

Hvidentl\ every photograph by itself gives the relative azimuth 
of every ])oint in it from the pointing of the camera, /. e., from 
the prolongation of the optical axis of the lens. So that if we 
measure on the i)rint from the principal line (a vertical approxi- 
mately in the centre of the view) to the right or left to any point 
the distance will express the tangent of its azimuth in terms of 
the focal length as unity. In utilising the photographs, however, 
we have nothing to do with angles, but only with their linear 
measure, and these are all referred to the focal length as con- 
stant. If now, from the triangulation, we know the al)solute 
azimuth of one point shown in the ])rint, then we can lay off on 
the plan the relative azimuth of such point and thereby obtain 
the pointing of the camera. This now being known, the abso- 
lute direction of any ])oint in the photograph immediately fol- 



Otto J. Klotz. 399 

lows. Hence by means of the triangulation lines the photo- 
graphs are oriented. From what has been just said it follows 
that a view containing no triangulation point may be oriented, 
provided it joins and laps one that has been oriented. Obviously 
for every point that can be recognized as identical on two views 
from different stations we have the direction from each station, 
and therefore know its absolute position, — being at the intersec- 
tion of the two directions. As man^^ points as can thus be recog- 
nized, just so man3' points can be plotted, and their distances 
known from the station. 

In this manner we exhaust all desirable common points on the 
prints and transfer them to the plan. This eliminates the hori- 
zontal element of our perspective; we have next to deal with the 
vertical element, the one that expresses the topography. 

Just as the principal line serves to measure the relative azimuth 
of any point, so the horizon line, which is drawn on the print 
between the lateral comb marks, serves to determine the eleva- 
tion or depression of any point above or below the level of the 
camera. 

Remembering that we now know the position and distance of 
the point whose height we wish to establish, the simple geometri- 
cal relation of similar triangles which subsists between focal 
length, absolute distance of point from station, and linear meas- 
ure on print of point above or below horizon line, immediately 
gives us our fourth term in the proportion, /. e., the linear meas- 
ure expressive of the elevation of the point, and this measure is 
converted into feet by applying the ratio on which the map is 
constructed, that is, the scale. For the purpose of facilitating 
the graphical solution of similar right angled triangles, a trian- 
gular scale printed on card board 11 inches by 27 inches is used. 
The triangular scale is a large right angled triangle, subdivided 
by equidistant perpendiculars on the base and by radiating lines 
from the acute angle. To each point thus determined is written 
its height above the sea. When a terrene is filled with a sufficient 
number of established points, the contour lines, 250 feet apart, 
are drawn. This requires skill, for, with photograph in hand, 
the expert topographer sketches in details not indicated by the 
plotted points. 

Points, as the shore line of lakes, islands and rivers, lying the 
same horizontal plane are readil3' plotted from a single photo- 
graph taken from an elevation of known height. The altitude 
must be sufficiently great so that the angle of depression is not 
too small. From an elevation of 3,000 feet above a horizontal 



400 The Vnriubk Star 859S U Pcgusi. 

plane one can plot without difficulty points on it distant fully 
three miles. 

In its broad outlires the plottinjj^ of plioto^raphs is nothing 
more than a continual j^raphical solution of rij:;lu anj^Hed trian- 
gles. 

We have taken some 3,()()() jiliotographs, and have covered, ap- 
proximately, 14.,0<JU stjuare miles, with our ])hotographic work. 

The photo-topogra])hic work, I'ltliough perfection is not 
claimed for it, will undoubtedly displace the older methods of 
survev for highly mountainous areas, for its superiority over 
them has now been permanently established. 

View .No. 3 is from a station, altitude 4,319 ft., on the west side of tlie north- 
ern part of Thomas Bay and looking? easterly across the Baird Glacier, showing 
its terminal, which almost reaches the sea— shown on the rijtjht hand. The view 
well illustrates the " Haw " of a f>lacier, which shows (the ice being a brittle and 
not a viscous mass) all the characteristics of the behavior of water, such as, the 
greatest velocity towards the center, the thread, eddies and falls. 

From jjliotograplis taken at intervals coverinj^ several months and from the 
same stations on the tluvio-glacial deposit lyinj^ between the ice front and the sea 
I determined the rate of motion of tlic front of this glacier to be about one foot 
per day during the period of observation. It is believed that this is the first ap- 
plication of the camera for determining the rate of motion of glaciers. 

View No. 4, shows that all in Alaska is not ice and snow and rock, but that 
along the sea shore the vegetation is rank ; ferns, brakes, mosses, the Devil's club 
and other forms vying with each other in their luxuriant growth for supremacy. 
The particular localitv represented is in the south side and near the entrance of 
Bradficlil Canal. Other illustrations explain themselves. 



THE VARIABLE STAR 8598 U PEGASI. 

PAUL S. VliNDELL. 



POK I'OI'fl.AH .XSTKDNO.M V. 

One of the most interesting cases of variability which have re- 
centlv been diseovered is that of V Pegasi, of which a short 
notice was ])ublished in the I'opil.vk Astko.nomv for December, 
1895, by Mr. John A. Parkhurst. 

In September, 181)4-, in tiie course of a corresjiondence with Dr. 
Chandler relating to certain suspected variables, I received an 
intimation horn him that he strongly suspected that he had 
found a variable of the Algol-type, the second found by him dur- 
ing that season (the first being Z Herculis). 

His next letter, dated Sept. 23, contained the means of identi- 
fving the star, and the suggestion that its period might possibly 
be about 2.0G days. 



PLATE XIV. 
Alaska Boundary Survey. 




No. 3. The Baird Glacier. 

Reproduction of Photograph by the Canadian Commission Officers. See page 400. 




No. 4. At Sea Level. 

Reproduction of Photograph by the Canadian Commission Officers. See page 400. 



tt 



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V 

6 

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PLATE XY. 
Alaskan Boundary Survey. 




No. 5. In Frederick Sound. 

Reproduction of Photograph by the Canadian Commission Officers. 




No. 6. Bradfield Canal. 

Rpnrnrllirtinn nf Phntno-ranh hv tht. Tanarlian rnmmissi 



PLATE XVI. 
The Alaska Boundary Survey. 




No. 7. The Devil's Slide. Lynn Canal. 

Reproduction of Photograph by the Canadian Commission Officers. 




Parliament Building.— Ottawa. 

Reproduction of Photograph by the Canadian Commission Officers. 



;onthly except July and August. 



27 



Annual Subscriptior Price $2.50. 




[E Stretcheth out thp; North Over the E:mpty Place akd Hangeth the Earth on Nothing 



March 1896 

CONTENTS 

k.la.skan Boundary Survey Plate XL 

The Discovery of an Unseen Body in the festellar System, F 70 Ophitichi. 

(Plate XII). Eric Doolittle 329 

phe Spectroscope in the Study of Variable Stars. Taylor Reed 333 

L Method of Measuring the Distances, Dimensions and Masses of 

Binary Systems by the Use of the Spectroscope. F. R. Moulton 337 

The Photography of Planetoids by Professor Max Wolf. (Abstract). 

Dr. E. S. Holden 343 

The Planet Mars. W. W. Payne 345 

Llaskan Boundary Survey. Otto J. Klotz 348 

The Graphic Construction of Eclipses and Occultations. III. Occulta- 

tions, (Illustrated). Wm. J. Rigge, S. J. 353 

"Jew Photographic Discovery. — The Solar Corona Photographed in Day- 
light. Chief Characteristic of the Corona. D. E. Packer 361 

The Lunar Ephemeris. Dr. J. Morrison 362 

The Planets and the Constellations for February. H. C. Wilson 370 

Practical Suggestions 377 

General Notes 379 



EDITORS: 

William W. Payne, Charlotte R. Willard, 

(Abroad for the year.) 

GooDSELL Observatory of Carleton College, 



Popllhr Astioimniv 




OENrEAL SCHOOL OF MEOHANIOAL ENGINEERING. 

DAVENPORT, IOWA. 



Popular Astronomy 



POOLE BROTHERS' 
CELESTIAL PLANISPHERE 

A MOVABLE CHART OF THE HEAVENS. 

Designed to show the Student the places of 
the Constellations at any given moment. 

For the use of Observers, the Publishers have for sale Star Charts, being SPECIAL 
SHEETS of the PLANISPHERE printed on a suitable paper, so that the Student may 
make and keep a Record of any Celestial Phenomena of Special Interest, such as the 
Paths of Planets, Comets, Shooting Stars, etc. 

POOLE BROTHERS' 
CELESTIAL HANDBOOK 

CONCISE AND ACCURATE. 

Companion to the Celestial Planisphere and 
Explanatory of its uses, besides other desir- 
able Astronomical Information for both the 
Amateur and the Advanced Student. 



// is difficult to imagine Jiow astronomy could be studied under inore fanorable 
auspices than with this Planisphere and the very elegafitly illustrated descrip- 
tive Handbook accompanyijig it. — Scientific American, Feb. i8th, i8gj. 



THE MOON 



A NEW AND COMPLETE MAP OF OUR SATELLITE. 

Compiled by Jules A. Colas; size 24K x 29 
inches; diameter of Lunar disc 20X inches. 
Printed with blue background, representing 
the color of the sky in full moonlight, the disc 
being colored to represent well the seas, 
plateaus, mountains, craters and streaks as 
they appear in the telescope. 

Accompanying the map is a full index 
Pamphlet of twenty-four pages, with notes by 
Prof. W. W. Payne. 

For Descriptive Circulars and other information, addi^ess 

Poole Brothers, 

316 Dearborn Street, CHICAGO, ILL 

WILLIAM WESLEY k SON, 

AC3 ErslXS, 

28 Essex Street, Strand, London, Eng. 





^f^ 



i 



Si 

i 
I 
P 

1/1 



^ 
% 



Bquatodal 



W'c have made Hquatorial Telescopes of 
the lari^est size and have also in process of 
construction a line of smaller sizes for Educa- 
tional Institutions and Private Observatories. 



VaRNER & SWASEY, 

CLEVELAND, OHIO, U.S. A. 



lonthly except July and August. 



28 



Annual Subscript! 




He Stretciikth out the North Oyer the Eiipty PlacB and Hangeth the Earth on Nothing 



April 1896 

CONTENTS 

Frontispiece, The Canals of Mars. Plate XIII 

The Planet Mars. IF, W. Payne 385 

The Spectrum of Mira (o Ceti). (Illustrated). H. C. Wilson 390 

Astronomical Work of Dr. W. L. Elkin. S. C. Chandler 392 

jAlaska Boundary Survey. Plates XIV, XV, XVI. Otto J. Klotz 395 

The Variable Star 8598, U Pegasi. (with Chart). PaulS. Yeadell. 400 

Observations of Short Period Variable Stars. W. E Sperra 404 

Galileo's Work on Saturn's Rings.— A Historical Correction. B. A. Part- 
ridge and H. C. Whitaker 408 

The Graphic Construction ot Eclipses and Occultations IV Occultations 

of Clusters. (Illustrated). Wm. F. Rigge, S. J 414 

The Planets and the Constellations for April with Chart. H. C. Wilson 425 

Comet Notes 432 

Practical Suggestions 437 

General Notes 437 

Book Notices 440 



EDITORS: 

William W. Payne, Charlotte R. Willard, 

(Abroad for'the year.) 

GooDSELL Observatory of Carleton College, 
KinRTTjPTKT.n MTNNnsnTA. r; « a. 



Populnr Astronomy. 



iEe. N. SAESfedLLER 



WASHINGTON, D. c. 




Maker of 



- TELESeePES 



MOVNTKD ICiilATOHIAI^l^V or PI^aiS, 



Popular Astronomy. 



POOLE BROTHERS' 
CELESTIAL PLANISPHERE 

A MOVABLE CHART OF THE HEAVENS. 

Designed to show the Student the places of 
the Constellations at any given moment. 
For the use of Observers, the Publishers have for sale Star Charts, being SPECIAL 
SHEETS of the PLANISPHERE printed on a suitable paper, so that the Student may 
make and keep a Record of any Celestial Phenomena of Special Interest, such as the 
Paths of Planets, Comets, Shooting Stars, etc. 

POOLE BROTHERS' 
CELESTIAL HANDBOOK 

CONCISE AND ACCURATE. 

Companion to the Celestial Planisphere and 
Explanatory of its uses, besides other desir- 
able Astronomical Information for both the 
Amateur and the Advanced Student. 



// is difficult to imagine how astronomy could be studied under more favorable 
auspices than with this Platiisphere and the very elegantly illustrated descrip- 
tive Handbook accompanyiftg it.—Scietttific American, Feb. i8th, iSgj. 

THE MOON 

A NEW AND COMPLETE MAP OF OUR SATELLITE. 

Compiled by Jules A. Colas; size 24K x 29 
inches; diameter' of Lunar disc 20X inches. 
Printed with blue background, representing 
the color of the sky in full moonlight, the disc 
being colored to represent well the seas, 
plateaus, mountains, craters and streaks as 
' they appear in the telescope. 

Accompanying the map is a full Index 
Pamphlet of twenty-four pages, with notes by 
Prof. W. W. Payne. 



For Descriptive Circulars and other information, address 

POOLE Brothers, 

316 Dearborn Street, CHICAGO, ILL 

WILLIAM WESLEY k SON, 

AGENTS, 

28 Essex Street. Strand, London, Eng. 



BlBBi5E»&STy?lSltE*!£l!ESBffE5EffE5eeEffl=J?&?^ 



P 

£ti 



i 



g 



i 




Equatorial 
ITclcecopee 



We have made Equatorial Telescopes of 
the largest size and have also in process of 
construction a line of smaller sizes for Educa- 
tional Institutions and Private Observatories. 



VaRNER El SwASEY, 

CLEVELAND, OHIO, U. S. A. 



>>■,«■ 






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LIBRARY OF CONGRESS 



014 432 070 



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